Defect-engineered ultrathin VSe2−x 3D architectures coupled with redox-active graphene for high-energy hybrid supercapacitors enabling regenerative energy capture and reutilization in modern elevators

High-performance supercapacitors are increasingly recognized as auxiliary power units for applications requiring rapid energy capture and delivery, including electric transportation , smart infrastructure, and industrial regenerative energy recovery. Here, we report a binder-free, selenium-deficient VSe2−x nanosheet architecture directly grown on 3D-Ni framework using a controlled hydrothermal route. With optimized conditions, we achieved a defect-rich structure that forms a highly wetted, interconnected network with a larger surface area and excellent electrochemical activity. As a result, the VSe2−x@Ni electrode delivers an impressive reversible capacity of 691.5 mAh g⁻¹, mainly enabled by diffusion-driven vanadium redox transitions and fast ion movement through the vacancy-rich pathways. To balance this ultrahigh capacity, a p-phenylenediamine (PPD)-functionalized graphene negatrode was employed, combining graphene’s rapid EDLC response with additional pseudocapacitive redox contributions. This complementary electrode pairing enables a hybrid supercapacitor with a capacitance of 224 F g⁻¹, an energy density of 79.9 Wh kg⁻¹ at 648.6 W kg⁻¹, with > 95% coulombic efficiency. As a proof of concept, the device was integrated into a regenerative elevator prototype, where it efficiently harvested deceleration pulses to power auxiliary loads. This synergistic electrode design bridges the energy-power gap in hybrid supercapacitors, offering a scalable strategy for next-generation energy recovery in vertical mobility and beyond.